How Are LED Strip Lights Manufactured?

How are LED strip lights manufactured?

A quality focused manufacturing process to create the best strip lights in the market

Introduction

LED strip lights may appear to be a simple product to produce and compared to other complex lighting systems, they are. However, it’s important to understand the manufacturing process so you can ask your LED supplier educated questions when determining the quality of a product. If you plan to use a product for the next 15 years in your home, business, or OEM project, it is essential that you ask your suppliers to back up their quality claims with data and science. Read this to find out What makes a high-quality strip light.

What is a LED strip light?

A LED strip light is a flexible circuit board populated with surface mounted LEDs and resistors. A main feature of the strip light is an adhesive backing that allows installation almost anywhere you would want to add lighting. They are low profile and you can cut the strip to your desired length along designated cut lines, allowing you to freely design your project without worrying about space requirements.

LED strip lighting can be manufactured to suit many different applications. The LEDs are selected before production to match the brightness, color, or lighting features. You can see the differences between LED chip sizes here in this article.

Strip lights are typically classified into one of four output categories:

• Static White and Single Color Output - Single color emitting LEDs like blue, red, green, yellow, ultraviolet, infrared, and multiple color temperatures of white which are named by their color temperature such as 2400K, 3000K, 4200K, etc.
• Color Changing (RGB) Output- The ability to control your LED chips to create just about any color you want
• Color Changing RGB + White (RGBW) Output - The same as above but the strip is also populated with white output LEDs so you can switch between RGB mode and white mode, or a mix of the two using a controller
• Dynamic Tunable White Output - Allows the user to adjust the color temperature output from a single strip light. They are manufactured with alternating LEDs of different color temperatures, so half of the LEDs are a lower temperature and half are a higher color temperature, allowing the strip to produce any specific color temperature between the two color temperatures of the LEDs.

The following is how we at Flexfire LEDs create some of the highest quality strip lights on the planet (and currently in orbit). We do not claim to follow any other manufacturer’s methods nor are assuming they follow ours. We believe in educating the world about this amazing technology and hope you are all as uncompromising about quality as we are when it comes to your projects!

The following is our Flexfire LEDs method (condensed, see next steps for details):

1. Understand and order your components
2. Quality Control Part 1
3. Dry the LEDs
4. Quality Control Part 2
5. Create and use solder molds
6. Apply lead-free tin solder paste onto the base PCB
7. Quality Control Part 3
8. Placement of components on solder pads
9. Quality Control Part 4
10. Bake the strip in a reflow oven to secure all components
11. Quality Control Part 5
12. Separate and join the 0.5m strip segments together
13. Quality Control Part 6
14. The tape is applied to the back of the PCB
15. Soldering wire leads and connectors onto each strip
16. Glue and heat shrink is applied to wire solder points
17. Waterproofing and weatherproofing for IP64 to IP68 rated strip lights
18. Age Testing
19. Quality Control Part 7
20. Rolled neatly onto a reel
21. Quality Control Part 8
22. Arrival in the warehouse - Internal testing - Quality Control Part 8
23. Final step - Quality Control Part 9

Like many top-of-the-line products, it is best to start with the highest quality components. Take the time and effort to select the perfect components for the strip. They cost more than other components of less quality, but they are worth it.

Manufacturing can begin once the following components are acquired:

• Flexible Printed Circuit Board
  • 2-4oz double-layer pure copper flexible circuit boards provide the best conductivity and heat dissipation. Remember, heat shortens the lifespan of a LED, so it’s best to get rid of it!
• SMD LEDs (The most important component!)
  • LED dies packaged with the highest quality of thermal pads, die bond materials, phosphors, and 99.99% gold bond wires.
  • Rigorous testing with LM-80 and TM-21 reporting.
  • Don’t just compare “ LED sizes”. The longevity and performance of two 5050 sized LEDs from any two manufacturers will differ greatly. Ask for the data and certifications.
  • High CRI, Gamut Index, Fidelity Index, and Saturation - explainer article here
    
• Resistors
  • Resistors are selected to match the forward voltage of the LEDs. The value of the resistor may change from batch to batch. Use a reputable company for resistors.
  • High-quality resistors are equally important, as skimping on this component will lead to premature failure of your strip light.
  • Do not overpower your LEDs! They will appear brighter at first but will fail fast. We know a few of our competitors that do this. The excess heat may also be dangerous if installed on flammable materials.
• UL listed wires and connectors
  • Always select components that are tested for safety and durability.
• Thermally conductive tape with very high bond
  • We use 3M brand VHB tape. Many suppliers offer no-name or worse, fake brand name adhesives. The key to a long-lasting installation and thermal conductivity is a great quality tape.

Once the components are received in the production warehouse, they are tested and checked to ensure they are accurate and pass through the rigorous quality checklist. This is an obvious but extremely important step.

Once we have the materials, we can begin our manufacturing journey in the LED drying room. The phosphor on the LED is still wet, so we place them into ovens at 158 degrees F for 12 hours, to dry them out.

When they are dry, test the LEDs again to make sure the photometric data and bin are on spec with what is to be produced. Light data consists of correlated color temperature (CCT) and color rendering (CRI). When passed through this stage, they are labeled, rolled up, and are ready to be placed onto the PCB.

Aluminum molds are created for each strip light design. They are cutouts (stencils, jigs, etc.) that go on top of the bare PCB in order for the solder paste to be perfectly spread over it.

Twenty-four loosely attached strips of bare PCB, 0.5 meters in length, make up the ‘PCB sheet’. It is placed under the mold and a lead-free solder paste perfectly fills the holes on the mold, creating flawless solder pads.

Another QC step makes sure that each solder point has just the right amount of solder paste and is prepared for the components to be placed on the solder points.

Next, the PBC sheet is placed into an SMT placement machine, also known as a pick-and-place machine (PnP). This machine picks up and places the resistors and LEDs on the solder points with perfect accuracy and pressure. This machine is capable of 80,000 component placements per hour. Much faster than any hand in the west (or east)!

The PCB with all components attached is fed out of the machine, to be inspected again by quality control. If there is a misplaced part, it is noted and the sheet gets reworked until it passes inspection.

The components are not secured to the PCB until the solder paste has hardened. To do this, the PCB sheets are belt-fed into the reflow oven. The reflow machine is a long oven that has multiple zones where the temperature can be independently controlled as the PCBs pass through. We heard once it is possible to cook pizza in them but we are yet to verify.

When the PCB exits the oven, the solder paste has hardened and we are only a few steps away from calling them LED strip lights. Another round of quality control is important to make sure all of the LEDs light up with equal intensity. Sheets that are rejected are reworked or manually soldered until perfect.

Once passed through quality control, the 0.5m PCB sheets (made up of the 24 loosely attached strips) are separated and soldered end-to-end until they achieve the specified length. At this point I believe it is safe to finally call the product a LED strip light.

Once the segments are soldered together, QC tests all connection points to make sure the entire strip illuminates properly and the temperature of the strip is stable.

3M brand VHB tape is then adhered to the back of the strip. It is very important that a high-quality tape is used that will not only make sure the bond is strong, but will also be thermally conductive, keeping the heat low to add to the strip’s lifespan.

We’re not done yet! The lengths and connection types may vary, but each strip typically comes with pre-soldered wire leads.

Next, a few dabs of glue are placed over the connections and a heat shrink is attached to secure the connection.

OPTIONAL STEP: If the strip requires special waterproofing or a weatherproofing sleeve, they are moved to that area of the production line for completion before being tested once again (Quality Control Part 6.2)

When the strip has been completely assembled, it is moved into an aging room, where the strip is fully powered on and left for 8-12 hours. New strip designs are also placed in separate ovens to test for heat and humidity tolerance

The strips are again tested for quality after the aging room before moving to the next step.

The strip is then wound up on a plastic reel. This keeps the strip from damage and makes it very easy to transport and use in the field.

The strip is tested one last time before it is placed into an antistatic bag, sealed, boxed, and shipped to our distribution centers.

Once the strips arrive in our warehouse, we pass a large percentage through another QC process where we double check all components. We test for rigidity, strength, and consistency of the solder, temperature performance, and adhesive durability.

We test in-house to ensure that the LED color temperature bins (3 macadams ellipse or under) color rendering index, gamut index, and fidelity Index are accurate to spec and consistent with the previous orders. These are the most important indicators of lighting quality.

We don’t stop once it has been installed. The final quality control strip occurs when we contact every customer to make sure the product is working as intended and fulfilling its beautiful purpose.